“Betrayed” is a good way to sum up the way I felt about the non-ending of The Killing. After investing 13 hours in the show, not finding out who really killed Rosie Larsen was simply unacceptable. Worse, we don’t know why we didn’t find out. The finale wasn’t a cliffhanger — it was a train wreck.

But, as is always true with TV shows, not everyone agreed. Some loyal viewers were loyal to the end — and loved the finale. If you are among that group, we have good news for you. TV Line reported Tuesday that Michelle Forbes has signed on as a season regular for Season 2 as Mitch Larsen, Rosie’s mom.

Mitch’s story was the most heartbreaking part of The Killing and Forbes’ portrayal of the grief-stricken mom earned her an Emmy nomination. If we can believe executive producer Veena Sud, that means Mitch finally will learn the truth about who killed Rosie.

Sud also told TV Line that a second case emerges during the investigation and we’ll meet at least two new characters: Lt. Carlson, a “clean-cut, well dressed lawman in his 50s” and Alexi, a “scary looking, dark and frightening” teenager whose bad-boy persona is attractive to teenage girls. We don’t know whether Alexi is connected to Rosie’s murder or part of the new mystery.

The Killing returns in Spring 2012. Will you be watching? Are you still a fan of the series or was one season enough?